Thermoregulatory responses to the first shearing of male lambs born to ewes sheared or not at mid-gestation

Abstract

The prenatal environment during pregnancy can influence the development of the offspring. Shearing pregnant ewes can change intrauterine conditions, potentially enhancing the thermoregulatory adaptation of the offspring after birth. The aim of the study was to determine whether the thermoregulatory responses to the first shearing differ in male lambs born to ewes sheared or not at mid-gestation (groups Sh and Con). On day 80 of gestation (winter), 12 multiparous Merino ewes carrying a single male fetus were sheared, while 9 were left unshorn. At 11 months old, all lambs were sheared for the first time during late winter (August; Day 0). Rectal and tympanic temperatures were recorded daily for three days before shearing, and from Day 1 to Day 7, at 07:00 h and 15:00 h. Blood samples were collected daily at 07:00 h to determine triiodothyronine (T3) concentration. Rectal temperature and T3 concentrations were analyzed using the GLIMMIX procedure (SAS On Demand for Academics), while tympanic temperature was analyzed using the MIXED procedure for repeated measures. Both analyses included the treatment, the time, and their interaction as fixed effects. No significant effects of treatment or their interactions between treatment and time were observed on any response variables, however, time had a significant effect on these variables (P=0.0001). Lambs born to ewes sheared or not at mid-gestation did not differ in the studied thermoregulatory responses to the first shearing. Therefore, in the conditions of this study, pre-lambing shearing did not have long-term effects on the male offspring's ability to cope with cold stress.